Sebaceous Neoplasms With Rippled, Labyrinthine/Sinusoidal, Petaloid, and Carcinoid-Like Patterns: A Study of 57 Cases Validating Their Occurrence as a Morphological Spectrum and Showing No Significant Association With Muir–Torre Syndrome or DNA Mismatch Repair Protein Deficiency

Molecular Genetics of Sebaceous Neoplasia

Sebaceous neoplasia primarily includes sebaceous adenoma, sebaceoma, and sebaceous carcinoma (SC). Sebaceous adenoma, sebaceoma, and a subset of cutaneous SC are frequently associated with defective DNA mismatch repair resulting from mutations in MLH1, MSH2, or MSH6. These tumors can be sporadic or associated with Muir-Torre syndrome. SCs without defective DNA mismatch repair have ultraviolet signature mutation or paucimutational patterns. Ocular SCs have low mutation burdens and frequent mutations in ZNF750. Some ocular sebaceous carcinomas have TP53 and RB1 mutations similar to cutaneous SC, whereas others lack such mutations and are associated with human papilloma virus infection.

Ocular Adnexal Adenomatoid Sebaceous Gland Hyperplasia: A Clinical and Immunopathologic Analysis in Relation to the Muir-Torre Syndrome

The purpose of this study is to codify the microscopic diagnostic criteria for ocular adnexal brow and caruncular sebaceous gland hyperplasias (pseudoadenomatoid) that distinguish it from an adenoma. Clinical records and photographs were critically reviewed and microscopic slides were stained with hematoxylin and eosin and immunochemically stained for adipophilin, androgen receptor, p16, p53, a spectrum of cytokeratins, Ki-67 and mismatch repair nuclear protein expression for MLH1, MSH2, PMS2, and MSH6. The patients and their close relatives had no history of cancer. Cytokeratin 7 and especially cytokeratin 17 highlighted the presence of ducts in the hyperplastic lesion, which are not present in adenomas. p16 and p53 were negative and Ki-67 immunostaining demonstrated similar low proliferation indices for normal and hyperplastic glands. The mismatch repair nuclear protein expressions were preserved in both lesions. Histopathologic misdiagnosis of adenomatoid sebaceous gland hyperplasia as an adenoma can lead to the impression of an association with the Muir-Torre syndrome. Cytokeratins 7 and 17 immunostaining can be helpful in highlighting compressed ducts that in exuberant sebaceous gland hyperplasias may lead to a diagnosis of an adenoma (in which ducts are absent). Negative immunostaining for p16 rules out a possible etiologic role of human papillomavirus in hyperplasias and the negative p53 staining indicates the lesions are not truly neoplastic. The preservation of mismatch repair nuclear protein expression rules out the likelihood of the Muir-Torre syndrome. The current cases convincingly establish that sebaceous hyperplasia is not associated with the Muir-Torre syndrome by both clinical findings and immunohistochemical testing.Two yellow lesions, from the brow and caruncle, were examined microscopically and immunohistochemically to establish the diagnosis of sebaceous gland hyperplasia and to rule out the Muir-Torre syndrome.

Sebaceous Tumors of the Skin: A Study of 145 Lesions From 136 Patients Correlating Pathologic Features and DNA Mismatch Repair Staining Pattern

ABSTRACT

Sebaceous neoplasms occur sporadically or in the setting of Muir-Torre syndrome. The data regarding the correlation of pathologic features and DNA mismatch repair (MMR) staining pattern in sebaceous tumors of the skin are very scanty and based on relatively small series of patients. The goal of this study was to correlate MMR staining pattern with selected morphological features in a series of 145 sebaceous neoplasms (sebaceous adenoma, sebaceoma, and extraocular sebaceous carcinoma) from 136 patients. Cystic change, intratumoral mucin deposits, squamous metaplasia in the absence of keratoacanthoma-like changes, ulceration, intratumoral and peritumoral lymphocytes (in cases without epidermal ulceration), and intertumoral heterogeneity proved to be significantly associated with MMR deficiency. Identification of any of these changes, alone or in combination, should prompt further investigation of the patient to exclude Muir-Torre Syndrome. Our study also confirms the previously published observation that the diagnosis and tumor location are significantly associated with MMR deficiency.

Update on the pathology, genetics and somatic landscape of sebaceous tumours

Cutaneous sebaceous neoplasms show a predilection for the head and neck area of adults and include tumours with benign behaviour, sebaceous adenoma and sebaceoma, and sebaceous carcinoma with potential for an aggressive disease course at the malignant end of the spectrum. The majority of tumours are solitary and sporadic, but a subset of tumours may be associated with Lynch syndrome, also known as hereditary non-polyposis colon cancer (HNPCC) and previously referred to as Muir-Torre syndrome (now known to be part of Lynch syndrome). This review provides an overview of the clinical and histological features of cutaneous sebaceous neoplasia with an emphasis on differentiating features and differential diagnosis. It also offers insights into the recently described molecular pathways involved in the development of sebaceous tumours and their association with Lynch syndrome.

Sebaceoma of a Meibomian Gland of the Upper Eyelid

Over a period of 1 year, a 74-year-old man slowly developed a painless left upper eyelid intratarsal mass. The skin was movable over the lesion. At surgery, a well-circumscribed, yellow-white, partially cystic tumor was encountered. Histopathologically it was composed of a random mixture of basaloid and sebaceous cells arranged in interconnecting cords. Immunohistochemical evaluation disclosed epithelial membrane antigen, adipophilin, and cytokeratin 14 positivity. These findings led to the diagnosis of a sebaceoma. The tumor cells abnormally failed to express mismatch repair proteins for MLH1 and PMS2. The patient did not have a personal history of any visceral malignancy, but his father had died at the age of 46 years and a daughter at the age of 33 years from colonic carcinomas. The implications of this periocular sebaceoma for the Muir-Torre syndrome are explored.

Intraductal sebaceous papilloma of a meibomian gland: a new entity possibly associated with the MSH6 subtype of the Muir-Torre syndrome

Over several months, a painless, multinodular, non-erythematous swelling of the deep tissues of his left upper eyelid developed in a 63-year-old man. An excisional biopsy with histopathologic evaluation disclosed a unique sebaceous papilloma within a cyst lined by non-keratinizing squamous epithelium that focally displayed a variably thick, superficial, eosinophilic cuticular layer. Immunohistochemical staining demonstrated that the tumor and its epithelial cystic lining had a profile consistent with Meibomian gland duct epithelium. Adipophilin highlighted cytoplasmic vacuolar lipid positivity. The encapsulation of the lesion, absence of nuclear atypia, and Ki-67 nuclear positivity restricted to the basilar cells established its intrinsically benign nature. The patient's clinical history was remarkable for pulmonary and colonic carcinomas resected, respectively, 20 years and 8 years earlier. DNA mismatch repair protein expression studies disclosed loss of nuclear immunostaining of MSH6 protein, pointing to the possibility of an underlying rare MSH6 variant of the Muir-Torre syndrome, not yet described in the ophthalmic literature. p16 nuclear positivity was also found in the tumor cells, indicating the possible role of high-risk human papillomavirus as an additional factor in the genesis of the tumor. Genetic evaluation of normal and tumoral tissues in future similar cases will detect if there is an underlying germline mutation versus a somatic mutation limited to the tumor. This will be required to fully establish a predictable linkage with this new subtype of the Muir-Torre syndrome.